Microsoft is putting its hero hat on this week. Redmond worked with members of the financial services industry and the FBI to scramble of a banking Trojan-horse program widely known as Citadel. The online sting saw more than 1,000 Citadel botnets taken offline.

According to Symantec, Citadel is a banking Trojan that has been doing its makers' dirty work since 2011. Like most banking Trojans, the security firm said, Citadel is a full crimeware kit. It provides the attackers with payload builders, a command and control (C&C) server infrastructure, and configuration scripts to target various banks. Citadel is a descendant of that other behemoth of the financial Trojan world, Trojan.Zbot (Zeus).

"Citadel is aimed at a more 'exclusive' attacker market than its more widespread predecessor, Zeus," Symantec's Orla Cox wrote in a blog post. "The Citadel kit is sold through underground Russian forums and typically costs around $3,000, compared to $100 for the SpyEye and leaked Zeus kits. Citadel users will also have to fork out a further $30-$100 to purchase Web inject code for the banks that they wish to target. Additionally, even if attackers have that money to spend, there is a strict vetting process with referrals required for new purchasers."

Weight of the Law

Symantec reports that Citadel infections have spread around the globe, but in the past six months the majority of infections have been in Australia, Italy and the U.S. While these take-downs may not eliminate the threat of Citadel completely, Cox said it certainly disrupts current campaigns and sends out a clear message to attackers that their actions are being monitored.

We caught up with Richard Westmoreland, a security analyst at SilverSky, to get his take on the take-downs. He told us out of all the bots, Zeus still remains infamous.

"Microsoft should be applauded for tackling the problem head-on, with appropriate credit also given to Agari [an e-mail security firm]. By taking legal action to disable resources used in botnets, it turns a virtual problem that is easy to ignore into a real problem that forces networking vendors to act," Westmoreland said.

"With enough momentum, these type of take-downs may fill a gap where regulatory compliance may not be applicable. Take-downs are disruptive and embarrassing to legitimate businesses and are best avoided via additional controls and security ."

Weight of Corporations

We also asked Ken Pickering, development manager, security intelligence at CORE Security, for his thoughts. He told us it's encouraging to see security firms taking an active stance against large criminal botnets.

"These botnets are responsible for millions -- if not billions -- in fraud, and they infect millions of PCs worldwide. Realistically, if firms like Microsoft, Symantec and Kaspersky don't tackle this problem, who will?" he asked. "Traditional law enforcement boundaries and skill sets don't usually carry over well onto the Internet, so decisive actions from these large companies are essential if we're ever going to stop this plague."